1. Field of the Invention
The present invention relates to a method of reading optical information and a method of recording optical information, and more particularly, to methods of reading and recording optical information in a recording medium using holography.
2. Description of the Related Art
Recently, as information and computer industries are rapidly being developed, there is an increasing demand for storage devices that can satisfy requirements for mass storage capability and high-speed data input/output. Therefore, a compact disc (CD), a digital versatile disc (DVD), a high definition DVD (HD DVD), a blue-ray disc (BD), a holographic digital data storage (HDDS), and the like are in the limelight as optical information storage devices capable of storing massive data and inputting/outputting data at a high speed.
Among various storage devices, a device of processing optical information using a holographic digital information storage, which will hereinafter be referred to as ‘optical information processing device’, records optical information using interference fringes formed by splitting a beam emitted from a light source into a reference beam and signal beam, and then allowing the reference beam and the signal beam to interfere with each other at a recording medium made of a refractive material such as a photopolymer. To read optical information, the reference beam input during the recording of the optical information should be restored and irradiated to the interference fringes of the recording medium. Thus, a reproducing beam generated by the diffraction at the interference fringe is detected, and the optical information is then acquired from this reproducing beam.
Meanwhile, the optical information processing device may use various kinds of multiplexing methods to increase the recording capacity.
Examples of the multiplexing method may include an angular multiplexing method, a phase-code multiplexing method, a wavelength multiplexing method, a shift multiplexing method, a peristrophic multiplexing method, a correlation multiplexing method, a fractal multiplexing method, and so forth.
In line with the development of multiplexing methods as described above, it is necessary to develop a method of efficiently detecting and determining a reproducing beam intended to be reproduced among reproducing beams generated from recording regions where several bits of optical information are recorded in an overlapping manner.
The present invention provides a method of recording optical information and a method of reading optical information that can easily detect and determine a selected reproducing beam intended to be reproduced.